1yoi

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spinqualitylabelsall models 1yoi, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

COBALT MYOGLOBIN (OXY)

Overview

The structures of the deoxy, oxy, and aquomet forms of native sperm whale, myoglobin reconstituted with cobalt protoporphyrin IX have been determined, by x-ray crystallography. As expected, cobalt myoglobin closely resembles, native iron myoglobin in overall structure, especially in their respective, aquomet forms. In the cobalt oxymyoglobin structure, the Nepsilon of, distal histidine 64 lies within hydrogen bonding distance to both the, oxygen atom directly bonded to the cobalt and the terminal oxygen atom, in, agreement with previous EPR and resonance Raman studies. The metal atom in, cobaltous myoglobin does show a small 0.06-A out-of-porphyrin plane, displacement when moving from the oxy to deoxy state. In the case of the, native iron-containing myoglobin, the oxy to deoxy transition results in a, larger 0.16-A displacement of the metal farther out of the porphyrin, plane, attributed to an increase in spin from S = 0 to S = 2. The small, displacement in cobalt myoglobin is due to a change in coordination, geometry, not spin state (S = 1/2 for both cobalt deoxy- and, oxymyoglobin). The small out-of-porphyrin plane movement of cobalt which, accompanies deoxygenation of myoglobin also occurs in cobalt hemoglobin, and serves to explain why cooperativity, although reduced, is still, preserved when iron is replaced by cobalt in human hemoglobin.

About this Structure

1YOI is a Single protein structure of sequence from Physeter catodon with SO4, COH and OXY as ligands. Full crystallographic information is available from OCA.

Reference

High resolution crystal structures of the deoxy, oxy, and aquomet forms of cobalt myoglobin., Brucker EA, Olson JS, Phillips GN Jr, Dou Y, Ikeda-Saito M, J Biol Chem. 1996 Oct 11;271(41):25419-22. PMID:8810310

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